This invention relates generally to photoplotter equipment, and more particularly a stand alone device for the on loading and off loading of media onto the curved surface of a drum or crescent-type plotting apparatus.
It has been found that drum type photoplotting apparatus of the type disclosed in aforementioned U.S. Pat. No. 07/839,398, present a significant advance in the imaging art by allowing imaging to be done in raster format onto a photosensitive media by supporting a media sheet on a partially cylindric support surface and controllably rotating a mirror along the center of curvature of that surface to effect such scanning. In order that the media be allowed to conform in this manner to the curvature of the support surface, it is necessary that each sheet have a very thin dimension, for example, on the order of 0.007 inches, hence making it highly flexible. One drawback to this is that the media sheet is somewhat mechanically unstable in terms of its being capable of being readily handled by an operator, thus making the overall plotting operation less efficient than it otherwise could be. That is, the drum plotter disclosed in co-pending U.S. application Ser. No. 07/839,398 is capable of rapidly scanning a number of media sheets in succession at a rate which is basically limited by the handling capacity of the operator. In the past, such manual handling operations involved the placing a film onto the support surface of a drum plotter so as to cause it to be held in alignment on that surface and subsequently scanned. Such manual placing of the media sheet onto the support surface of the plotter involved requiring the operator to insure that the media was also positioned accurately along a given datum referenced to the scanning operation. This step likewise added time and effort to the process. Additionally, the process of removing the thin film sheets from the curved support surface and then placing each sheet in a collecting tray was a further burden on the plotting operation. Through this all, the media which is made purposely sensitive to certain ranges of radiant energy, often including room light, must be handled in this manner in a dark room environment, which made the handling of the media within the already restrictive confines of the drum plotter, that much more difficult to manage.
A number of such drum plotters presently exist in the marketplace, which as mentioned, have been widely and successfully received in the marketplace. Thus, any solution to the aforesaid problems in the handling of media in a manner other than that which has been discussed above, must be made with the existing structure of these plotters in mind.
Accordingly, it is an object of the present invention to provide a media handling system for photoplotters using a crescent or drum shaped support surface wherein the media handled is in the form of a flexible sheet of material, i.e. film, which is advanced by the unit from a supply of such media onto the support surface of the plotter in registry with a given datum in the plotter and wherein after a scanning operation is completed on such media, it is automatically removed from the support surface of the plotter and returned to the unit and placed in a collecting tray.
It is yet a further object of the invention to provide a handling unit wherein media is handled in the aforementioned manner in a light-tight environment while maintained within the interior of the unit as well as while it is out of the unit.
It is a further object of the invention to house a stack of unexposed media or film in a light-tight cassette such that individual media sheets can be off-loaded and placed in registration onto the support surface for exposure by the scanning mechanism and subsequently be returned to a collecting station in the unit which is likewise sealed against light.
Still a further object of the present invention is to provide a transportable unit that is capable of handling media in the aforementioned manner which is adaptable to the existing structure of plotters which already exist in the market so as to mate with such units to create a light-tight passage therebetween for handling of media during a plotting operation therethrough.
A further object of the invention is to provide a supply cassette in which the media is caused to take on a given configuration conformable to the shape of the support surface of the plotter to which it is to be used so that the media is capable of being advanced onto the support surface in substantially the same configuration which it will assume when once placed on the involved support surface.
Yet, a further object of the invention is to provide a method of advancing thin sheets of film from a supply of such film onto the support surface in a photoplotter for scanning and subsequent removal by the apparatus and placement into a light-tight collecting tray for subsequent developing and/or processing.